Pin hole grinder



Feb. 9, 1937. J SUNNEN 2,070,381

PINHoLE GRINDER l Filed April-23, 1935 3 Sheets-Sheet 1 MJP;

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J. SUNNEN PINHOLE GRINDER Filed April 23, 1935 s sheets-sheet 2 /N VEA/T02: Jost-.PH .Sun/ve.

Hrrafz/VEK Feb. 9, 1937.- J. sUNNEN 2,070,381

PINHOLE GRINDER lFiled April 23, 1935 5 Sheets-Sheet 3 Flo.

Patented Feb. 9, 1,937

UNITED STATES PATENT OFFICE 2,070,381 PIN HOLE GIRINDIEIR. Joseph sumen, Kirkwood, Mo. Application April 23, 1935, Serial No. 17,819

6 Claims.

My invention has relation to improvements in grinding machines and consists in the novel features of' construction more fully set forth in the specification and pointed out in the claims.

The present invention is directed more particularly to machines for grinding small cylindrical holesgsuch as the Wrist pin holes of pistons, connecti'ng rods a'nd cylinders of small compressors,

etc. The invention is an improvement over that 1o described in my co-pendlng application, Serial No. 737,366, filed July 28, 1934, Iand like that of said application the grinding machine comprises a mandrel which carries an abrasive stone operable in the hole tolbe ground.v v

'I'he principal object of the present invention is to provide a pedally operated control which not only controls the rotation of the mandrel but also controls the feeding of the abrasive stone radially for carrying out the grinding operation.

A further object of the invention is to provide a'manual feed control for advancing the abrasive stone during the cutting operation, said manual control also serving the function of a limiting gauge to ix the limit of feed to which the abrasive stone may be advanced by the operation of the foot pedal. It is also one of the objects of the invention to regulate the tension of the drive belt automatically as the friction of the grinding operation increases.

The manner of accomplishing these objects, as Well as other advantages inherent in the invention, will be better apparent 'from a detailed descriptidn of the same in connection with the accompanying drawings, in whichz` Figure 1 is a front elevation of my improved grinding machine; Fig. 2 is a side elevation thereof showing a piston on the mandrel for the purpose of grinding the wrist pin holes thereof, and the foot pedal lbeing inthe raised position when the machine is idle; Fig. 3 is a front elevation of the front wall of the housing broken away to show the mechanism within the housing; Fig.` 4

is a side elevation similar to Fig. 2, however,.on l

the grinding machine on an enlarged scale with 'Y head, feed ro'd and the end of the mandrel connected therewith; Fig. 10 is a cross-sectional der tail taken on the line IIl--III of Fig. 9; and Fig. 11 is a cross-sectional detail taken on the line II--I I 'of Fig. 9.

Referring to the drawings, H represents a grind'- 5 ing machine housing on the top `I of which is mounted an electric motor M, on the shaft 2 of which is the driveA pulley 3 disposed toward the rear of the housing H.

In the front and rear walls 4 and 5, respectively, there are formed bearings 6 and 'I for a hollow spindle 8 held therein by shoulder, produced by the enlarged spindle head III, and the hub .II of a pulley I2 xed 'by a set-screw I3 to the spindle 8. Disposed above and in vertical alinement with the spindle 8 'is a rod I4 rotatably mounted in bearings I5 and I6 in the front and rear housing walls 4 and 5, respectively. The forward end I4 of the rod I4 is of reduced diameter andis provided with screw threads t for receiving a dial I'I and lock-nut I8l whereby the dial is securely fixed to the rod I4. 'Ihe dial II is provided With oppositely disposed wings I9, I9 anda handle 2U for ease of manipulation. The rearward end I4 of the rod I4 is -provided with screw threads for receivingA a threaded sleeve 2|, to which is pivotally connected by means of pins k22 the upper-end of a yoke comprising a pair of spaced bars 23, 23. The bars 23, 23 are maintained in xed spaced relation by channel pieces 24, 24 riveted or spot-welded to the bars 23 as shown. The lower end of the yoke has connection with a link 25 through the medium of a pivot pin 26, the opposite end of `said link 25 being connected to a pin 21 eccentrically fixed into the end of a rock shaft 28 rotatably mounted in a bearing 29 formed in side wall 30 of housing H, and a bearing 3l spaced from the bearing 29 and projecting from the rear wall 5l of said hous- Iing.

The rock shaft 28 is integrally formed with a lever 32 on the outside of housing H and extend- /ing forwardlythereof, said lever having an eye 33 at its forward end in which is secured one end of a exibleelement 34, such as a cord, said cordv 45 then extending upwardly over a pulley 35 and downwardly to a foot pedal 36, to which the ilexible element is also secured.

The pulley 35 is rotatably mounted on a reduced end 3'I of an L-shaped arm 38 traversing a slot s in housing wall '30 and vfixed into one end of `a rocking lever 39, secured by means 'of a set-screw 40 tp a rock shaft 4I mounted in bearings 42, 43 in the front and rear housing walls 4 an'd 5, respectively. The shaft 4I passes through the rear 55 wall 5 of the housing and is bent to provide a crank arm 44, on the end of which is mounted an idler pulley 45. The length and position of the crank 44 is such that the idler pulley 45 operates in contact with belt 46 passing over the motor pulley 3 and grinding machine pulley I2. The arm 38 is longer than the opposite lever arm 39,- into the terminal eye 48 of which is secured one end of a coiled spring 49, the opposite end of said spring being anchored to a pin 50 secured in housingl wall 4 near the bottom thereof. Thespring 49 `together with a braking member about to be described serves to hold the rocking lever 38, 39

in horizontal position (Fig. 3). l5 'I'he braking member comprises a bracket 5L having an opening 52 at its upper end whereby it is loosely connected to a bolt 53 secured in housing sidewall 54, and a belt 55 fixed at one end in an eye 56 in the lower end of bracket 5|, said belt being wrapped around the spindle 8 and having its other end fixed in a sceweeye 51 fastened into Y the lever arm 38.A 'Ihe lower'end of bracket 5| is anchored to the housing wall 54 byfa bolt 58 on which is coiled a spring 59. The lever 32 operates between a lower stop 68 and an upper stop 6|, said lever being held in contact with the lower stop 60`when the machine is idle' by reason of a coiled spring 62 connected between a pin 634secured in'housing wall 4 and a stem. 64 iixed in` 0 rock shaft 2s. 1n the operatibn of the machine the upper pin 6| serves as a stop for the lever 32 during the movement of all of the parts set in motion by the operator when he depresses the foot pedal 36.

k The driving mandrel 65, on which no claim is made in this application, is xed in the head I0 of l spindle 8, the set-screw 66 contributing to hold the mandrel securely in the head I0, and the longitudinally disposed grinding stones 61, 61 are adv i justed radially by the wedge-bar 68 connected to a feed rod 69 mounted. for longitudinal sliding movement in the spindle 8. 'Ihe feed rod 69 is supported by a bushing 10 xed into therear end of spindle 8 and by a slotted disk 1I fixed in the bottom of the spindle head I0 against a shoulder 12. A link 13 has a socket 14 into whichthe outer end ofthev feed rodl is secured and also has a transverse slot 15 near its free end to receive a .lip 16 turned over at the end of wedge-bar 68 of the mandrel 65. Thus, the wedge-bar is con' nected to the feed rod 69 so that longitudinal 'movement of the feed rod, either out or in, will be communicatedto the wedge-bar and effect adjustment of the grindingv stones 61, 61. The connection of the wedge-bar 68'J with a'sliding feed lrod for the purpose of adjusting the grindingstones is not new per se as such a device is shown in my co-pending application, Serial-No. '137,366 above referred to. rI'he novelty of the present invention is restricted to the grinding machine exelusive of the mandrel or other tool carried by the machine. A spring 11 is coiled about the feed rod 69 and has one end connected to a hook 18 projecting from the socket 14, and the .other end is xed in the bushing v10, the -tendency of the spring being to hold the feed rod rearwardly and take up the longitudinal play thereof. Since the feed rod69 rotates with the driving spindle 8.and

From the foregoing it is apparent that the l0- yoke comprising the` bars 23, 23 may be moved to operate the feed rod 69 without interfering with the rotation of said feed rod. It will be observed that the beveled face I1' of disk I1 has graduaition marks m, seme of which are numbered from l5 one to eleven. The spaces between'successive numbers are to indicate adjustments of the feed rod 69 to effect a grinding operation of .001". The spaces between the numberedlgraduations are again divided into ten parts to eiect adjust- 20 ments as small as .0001", all of which will be explained more in detail hereinafter. In order to facilitate the accuracy of these adjustments a bracket 89 is mounted on the housing H so as to project above the center of disk I1 and a vbase 25 graduation mark m' appears on the face of the bracket 89 to which the graduations on the disk face I1 are referred in order toeffect a reading.

The' operation of my improved grinding machine will be best understood from a detailed de- 30 scription thereof as follows :A

The loperation of the foot pedal 36 produces two. functions. It sets the spindle 8 and mandrel 65 in motion and it advances the grinding stones 61, 61 radially outwardly as the grinding opera- 3 5 tion progresses. Since the belt 34 passes over pulley 35 and is connected to the end of lever 32, said pulley will be pulled downwardly, and the lever 32 upwardly with a downward movement of the pedal 36. lOf course, the downward movement 40 of the pulley 35 rocks the lever arm. 38 downwardly and rotates the rock shaft 4| so that the idler pulley 45 will press against the drive belt 46 to tighten the same untilthe pulley I2 is driven by the motor pulley 3. The downward movement 45 of the lever arm 38 loosens the brake stra`p 55 Aso that the spindle 8 will rotate freely. When the pedal 36 is released the lever 32 and the lever arm 38 will be restored to their at rest positions under thetension of springs'62 and 49, respectively, and 50 the. idlerl pulley 45 willi'move away from the belt 46 which will become slack and ride freely over the pulley I2. The upwardmovement of the lever arm 38 under the tension of the spring 49 tightens the brake strap 55 around the spindle 8 55 causing said spindle to come to rest almost immediately.

As the lever 32 is raised the rock shaft 28 is rotated and the eccentric pin 21 movesforward,

.drawing on the link 25 which oscillates the yoke 23, 23 about the pivot pin 22. This oscillation of the yoke pushes the feed rod 69 forwardly so that the wedge-bar 68 will advance the grinding stones 61, 61 radially outwardly. Thus, when the operator steps on the pedal 36. he notfonly causes the mandrel 65 to rotate, but also feeds the grind-- ing stones. The l harder vhe steps down on the pedal 36 forthe purpose of speeding up the grinding operation the more tension is automatically imposed /on thebelt 46 by the idler pulley 45. While it is possible to feed the grinding stones 61, 61 into the work by the operation of -the disk I1 alone it Iis' preferablethatthis disk be used as a stop gauge to set thelimit to which the stones 4oversize pins. The rst grinding operations restore the wrist pin holes to true cylindrical shape. After this is accomplished the operator calibrates the holes to find out how near they are to the correct size for receiving the new wrist pin. We will assume that the calibration shows that the holes must be increased in size about .003". The operator now rotates the hand operated dial I1 in a counter-clockwise direction soas to move the upper end of the yoke rearwardly to withdraw the feed rod so that the stones 61, 61 will'be retracted andclear of the wrist pin holes when the foot pedal 36 is depressed to raise the lever 32 its maximum amount to encounter the stop pin 6I. Now, with the footl pedal depressed, the operator turns the dial I1 in a clockwise direction until the stones 61, 61 have been forced outwardly sufficiently to operate lightly within the wrist pin hole. The operator now releases the foot pedal 36 so that the stones will be withdrawn by the release of the lever 32 which is now pulled downwardly in contact with the stop pin 60. With the foot pedal released the operator now turns the dial I1 three graduations in a clockwise direction which -advances the stones 61, 61 .003 so that when the foot pedal is again depressed its maximum amount the stones 61, 61 will be .003 further advanced than they were before the dial l1 was last adjusted.

Thus, the hand dial l1' may be used to determine the maximum advancement of the stones 61, 61 by the operation of the foot pedal to perform the grinding operation. -Whe'n the foot pedal is entirely depressed and the lever 32 reaches its uppermost position'in contact with stop pin 6| the. grinding operation is completed as the desired .003 has been removed from the wrist pin holes.

I f the operator should find that the .003 that has been lground from the hole in the preceding operation has not enlarged the hole suciently and a very small additional amount of grinding is necessary he may keep his foot on thepedal 36 so as to hold the lever 32 in contact with vstop pin 6I and, by means 'of the hand dial I1', adjust the grinding stones 61, 61 so as to advance them any amount from .0001 and beyond. Thus, in

addition to `using the hand dial I1' as a stop gauge to set the limits of the grinding' operation this dial may be used to effect minute adjustments of the grinding stones such as are necessary when the grinding operation is near completion,

Having described my invention, I claim:

1. A grinding machine comprising a housing, a spindle mounted in said housing, a grinding tool fixed in the head end of said spindle, said tool including a radially movable grindingelement, a feed rod mounted for longitudinal movement in said spindle, means interconnecting the grindspindle mounted in said housing, a grinding tool fixed in the head end of said spindle, said tool including a radially movablegrinding element, a feed rod mounted for longitudinal movement in said spindle, means interconnecting the grinding element and feed rod for adjusting' the former with a movement of the latter, a driving pulley,

means for actuating said pulley, a driven pulley on the spindle, a belt passing over said pulleys, a belt tensioning device therefor, an actuating pedal, connections between said pedal and feed rod. connections between the pedal and tension-- ing device whereby the belt tension is increased asthe pedal is operated to advance the feed rod, a brake operatively associated with said spindle and connected with the belt tensioning device whereby the brake is released as the pedal is operated, and means for automatically applying said brake when the pedal is released.

3. A grinding machine comprising a housing, a spindle mounted in said' housing, a grinding tool fixed in the head end ofsaid spindle, said tool including a radially movable grinding element, a

feed rod mounted for longitudinal movement in said spindle, means interconnecting the grinding element and feed rod for adjusting the former with a movement of the latter, means for rotating said spindle, a yoke having both swivel and pivotal connection with the feed rod, said yoke having an adjustable fulcrum at one end, and

means connected to the other end of the yoke for oscillating said yoke on said fulcrum.

4. A grinding machine comprising a housing, a spindle mounted in said housing, a grinding tool xed in the head end of said spindle, said` tool including a radially movable grinding element, a

feed rod mounted for longitudinal movement in said spindle, means interconnecting the grinding element and feed rod for adjusting the former tool fixed in the head end of said spindle, said tool including a radially movable grindingelement, a feed rod mounted for longitudinal move# ment in said spindle, means interconnecting the grinding element and feed rod for adjusting the former with a movement of the latter, means for rotating said spindle, a yoke having both swivel and pivotal connection intermediate its ends with the feed rod, a fulcrum member having pivotal connection with one end of said 'yoke, an actuating lever, suitable connections between 'said lever and the other end of the yoke for oscillating the same about said fulcrum, rotatable means for moving said fulcrum member to oscillate said yoke when the actuating lever is stationary, and a graduated dial associated with said rotatable means to indiote the .effective movement of the feed rod.

6. A grinding machine comprising a housing, a spindle mounted in said housing, a grinding tool fixed in the head end of said spindle, said tool including a' radially movable grinding element. 1

cillating said yoke on said fulcrum, and a clutch interposed between the spindle and rotating meanstherefor, automatic means for disengaging said clutch with the operation ot the means for oscillating said yoke.

JOSEPH SUNNE. 

